Conventionally, a composite processing device provided with a punch press part and laser processing part has been used. On this type of composite processing device, the laser processing part is arranged in order to perform detailed processing and the processing of complicated shapes such as those which can not be performed by punch processing but for reasons of operating costs and processing efficiency, punch pressing is mainly used. Thus due to these factors, press ability (punch ton amount) is an important specification of the punch press part.
However, when a large press ability is required of the punch processing, this is rarely used and as a punch press part having a large press ability is provided for this seldom used processing, the wasteful use of the equipment is great.
Furthermore, on this kind of composite processing device provided with a punch press part and laser processing part, the large vibrations of during punch processing influence the optical devices of the laser processing part thus maintenance of the high accuracy in the laser processing is difficult.
Conversely, in order to reduce the noise and vibration of the punch press device, it is preferable to reduce the speed at the instant when the punch tool contacts the work surface by changing the punch speed mid-stroke. This kind of speed change mid-stroke is normally impossible for mechanical press devices and requires a hydraulic press.
However, the equipment cost of hydraulic presses increases as a hydraulic unit is necessary. In order to solve this problem, the present applicant tested a device where punch driving was performed directly by a servo-motor. However, with direct driving by a servo-motor, obtaining enough press ability for punch processing when the work is thick or when the hole to be punched has a large diameter is difficult due to the limits of the motor output generally produced.